In the hours before Obama and Romney arrived to the University of Denver's Magness Arena, the crowds outside the perimeter of campus swelled dramatically. By 5 p.m., University Boulevard became an actual battleground, with Obama supporters on one side of the street shouting to Romney supporters on the other side. It was a clear and chaotic illustration of the passionately -- and very evenly -- divided voters that have given Colorado its status as one of the most important swing states in the country.

Mitt Romney supporters.

Sam Levin

As temperatures dropped and the wind picked up -- sending a diverse array of Obama and Romney signs and posters flying in the air -- both sides tried to outdo each other with their chants.

"Obama! Obama! Obama!" shouted the president's supporters, wearing green T-shirts and holding giant "Forward" signs as they crowded on one side of South University Boulevard near Buchtel Boulevard. On the other side, Romney fans with "Fire Obama" signs shouted back, "Go Mitt, go! Go Mitt, go!"

Obama supporters on one side of the street.

Sam Levin

Fire Obama folks on the other side of the street.

Sam Levin

"People are very polarized here with very opposing views," said J.J. Hendricks, 31, who had his son Daniel, three, on his shoulders.

Hendricks, standing on the Romney side, said he will probably vote for him, but came mostly just for the excitement of the event.

"Trains! Trains! Trains!" his son shouted, looking toward the light rail in the distance, seemingly oblivious to the partisan chanting. "Snow plows!" he added.

JJ Hendricks and his son Daniel, three.

Sam Levin

"He just wanted to see the fire trucks and police officers," his father said. "We just wanted to show him all the hoopla."

He added, "It's the most firetrucks he's seen in any one place.... We can't get all that close to the president or Romney but seeing the people who are here [is exciting]."

The crowd roared as the motorcades of the president and Romney allegedly went past, during which time Denver Police Department officers on side shouted that onlookers stick to the sidewalk.

Continue for more on the pre-debate madness.

Next to Hendricks, a group of DU students said they were there to make their support of Romney loud and clear.

"It's kind of inspiring just to see so many young people and students come out here to support," said Jessica Herring, eighteen.

DU supporters.

Sam Levin

"It's overwhelming," added her friend Natalie Bell, eighteen.

Austin Metsch, another eighteen-year-old student, said he came because he didn't have much else to do. "It's something to do and I think he should be president."

He added, "Everyone is getting nice and rowdy."

"Mitt's the tits!" he shouted as he walked back into the crowd.

Some of the Romney supporters heckled a passerby with an Obama shirt, yelling at her, "Do you want to be Europe? No! This is America!"

Obama supporters.

Sam Levin

John Hopper, 45, who lives in Denver, added, "The energy is fabulous here."

Standing on the Romney side, he shouted, "We are obviously outnumbering them," just as a blue Obama/Biden sign came flying toward him in the wind and hit him.

He brushed it to the ground, crumpled it and stepped on it.

"Do you have a place for trash?" he asked a nearby DPD officer.

She did not.

John Hopper.

Sam Levin

Continue for more of the debate fever on campus and more photos.

The chaos of the event was perhaps even more pronounced inside the giant media room -- especially in the immediate aftermath of the debate.

Surrogates for Obama and Romney both wandered around with large signs to make them easily seen to reporters, who shoved, pushed and tripped over each other in efforts to stick their recorders in the faces of assorted low-to-high-profile officials in attendance.

Eric Fehrnstrom.

Sam Levin

"We gotta find a Democrat," one reporter shouted to his cameraman after recording an interview with Eric Fehrnstrom.

"I think they prepared equally, but I think the result was that Mitt Romney was the clear [winner]," Fehrnstrom told reporters, who were shouting over each other to get their questions in. "I was surprised that the president spoke in empty platitudes and had no vision for where he wanted to take the country, especially since he's been telling us this is a choice and it definitely is a choice. The choice is, do we want four more years like the last four years...or do we want a real recovery?... Governor Romney described in detail how he would make that come about."

Next to him, reporters crowded around former New York City Mayor Rudy Giuliani, another surrogate for Romney, "I don't think the president was ready to be challenged.... He was looking for his teleprompter and he didn't have it."

Rudy Giuliani.

Sam Levin

Just a few feet from Giuliani, Jim Messina, Obama's campaign manager, seemed to face the toughest and most intense questioning from dozens of reporters so jam-packed around him that some were shoving their recorders nearly on top of other journalists' heads.

"A lot of people said that the president looked a little tired. That he didn't have the fire, the passion that we saw four years ago," one reporter said.

"Look, you guys said the exact same thing about his convention speech. And what we did was talk to adults in this country.... We had a very clear vision. We had a real conversation with folks about where we're taking this country. That's what we are gonna do. That's who he is."

He continued, "The president [laid out] exactly what he wants to do. Governor Romney attacked pretty well. We understand that's what he had to do tonight, but he didn't lay out where he wants to take this country and I think that's a problem for the governor."

Jim Messina.

Sam Levin

A reporter shouted, "Are you saying that the president won this debate?"

"I believe the president did win this debate, absolutely. The president laid out a very clear difference in this election," he said. "Governor Romney stayed on the defense."

Continue for responses from some voters in attendance.

Meanwhile, supporters in the crowd -- braving the cold after the debate -- had mixed reactions.

Aaron Black, a prominent member of Occupy Wall Street in New York in attendance, said that he was shocked by how much it seemed Romney was flip-flopping on many issues. As we noted earlier, experts have also suggested that Romney's comments were much more centrist compared to the far-right politics he's previously espoused during the campaign.

"I've never seen somebody lie like that in front of the camera," he said, "just about his issues with not taxing the middle class and not being into trickle-down economics.... It was as if he just changed his plan within a week's time span.... He did a complete 180 on everything, except for getting rid of Obamacare. I just have a really hard time believing that he just changed his mind."

Still, he said, "I was surprised by how crisp Romney was."

Laura Burns, a graduate student and Obama supporter, said she was pretty disappointed with the whole debate.

Laura Burns.

Sam Levin

"I feel that both of them didn't really answer a lot of questions. We didn't get a lot of variety in what people were talking about," she said, noting that Obama was also not as aggressive as she wanted him to be.

Will that hurt him come Election Day?

"I don't know how much Americans really listen to the debates to make their decisions," she said.